This invention relates to circuit interrupters and more particularly to improvements in an operating mechanism of a circuit interrupter.
West German Pat. No. 19 04 731 discloses an electric circuit interrupter in which a movable contact arm having a movable contact is pivoted for opening and closing the circuit interrupter, on the movable contact arm there is pivotally mounted a releasable member for releasing the movable contact from a latched state the releasable member held a latch member, by an electromagnetic trip device and/or a bimetallic thermal trip device including a bimetallic element operable reponsive to heat. The latch member is pivoted on the movable contact arm and includes one end being in latching engagement with the releasable member, and another end thereof is pivotally connected to one end of a toggle mechanism. The other end of the toggle mechanism is pivotally connected to a manually operable operating handle.
When an overcurrent flows through the circuit interrupter, the bimetallic element is heated to deflect to such an extent that the free end of the bimetallic element pushes and rotates the releasable member which in turn releases the latch member from its latching position. As a result, the movable contact arm is pivoted to open the circuit interrupter. When a massive overload current much greater than the first overcurrent flows through the circuit interrupter, in addition to the above-described opening operation due to the deflection of the bimetallic element, the electromagnetic trip device generates an electromagnetic force which actuates a magnetic plunger to push and rotate the releasable member which in turn will also pull and rotate the latching member from its latching position and cause the movable contact arm to pivot to open the contact of the circuit interrupter to open. When it is desired to manually operate the circuit interrupter, the operating handle of the interrupter is moved. When the handle is operated, the toggle mechanism bridging between the handle and the latch member transmits the handle movement to the latch member and to the movable contact arm to pivot and open the contact of the circuit interrupter.
The operation of this circuit interrupter is quite satisfactory. However, it is desirable to provide a circuit interrupter having an operating mechanism simpler in structure.